Upon further investigation this actually appears to be ghasts spawning on peaceful. They can do this naturally or via egg if playing on creative.
Can also confirm this occasionally happens(on Realms), though unsure why. It is also possible to end up at an incorrect portal from Nether->Overworld(what I've experienced) if the Overworld portal you end at was "close enough" to the same Nether coordinates you went though.
This is the behavior eating has had in Nether portals for the past several updates, but something else is causing it now as well.
This bug is present on xbox. If you choose a classic skin (skin pack) in the character creator on the next load it will forget the skin used ojnthat character and replace with default steve or alex. This is worse than it was in 1.12.2 when most of the time you would have to wait until after sync to see the correct skin, now you have to wait until after sync and then manually set it every time.